qrcode plugin (zinc:qrcode)

QR codes from text, on Nayuki’s QR Code generator (C, MIT, version 1.8.0 in plugins/qrcode/vendor/). It is also the example of a C library made available to TypeScript on every engine with one C file: native/qrcode.abi.c is written on Zinc’s native ABI, so the same file is the plugin’s library on the computer (interpreter, AOT, QuickJS) and is compiled into the ESP32’s mquickjs firmware (native code on the ESP32).

import { encode, wifiText, HIGH } from 'zinc:qrcode';

const qr = encode('https://example.com');           // MEDIUM error correction, version 20 at most
for (let y = 0; y < qr.size; y++) {
  const runs = qr.runs(y);                           // start, length, start, length... of the dark modules of row y
  for (let i = 0; i < runs.length; i += 2) rect(x0 + s * runs[i], y0 + s * y, s * runs[i + 1], s, 0x000000);
}
encode(wifiText('home', 'secret'), HIGH);            // a phone's camera joins the network

• encode(text, ecc = MEDIUM, maxVersion = 20): a QrCode; a RangeError when the text does not fit (version 20, 97 modules a side, holds about 660 bytes at MEDIUM). ecc is LOW, MEDIUM, QUARTILE or HIGH.
• QrCode: size (modules per side), module(x, y) (dark or not), runs(y). Draw a light margin of 4 modules around it.
• wifiText(ssid, password): the WIFI: text phones read as “join this network”.
• On the ESP32 the two buffers are static (2.4 KB of RAM); a short URL encodes in a few milliseconds.

Example. examples/esp32-qrcode. Test. tests/t0/mquickjs_esp32.sh runs it under mquickjs with its C.

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